A programmable logic controller (PLC) is an industrial computer control system that is used to monitor states of a set of input devices, e.g., sensors, switches, or pushbuttons, and to ultimately control the state of various valves, motors, solenoids, pumps, relays, actuators, or other output devices. A typical PLC includes a central processing unit (CPU) and computer-readable code instructing hardware elements of the PLC how to perform motion control functions such as input state detection, program execution for the various controlled workstations, control of the output devices, and communication with networked devices. Languages such as a Ladder Logic, Structured Text, or low-level assembler languages can be used in overall PLC control.
A human-machine interface (HMI) device facilitates direct interaction between a machine and a human operator. An HMI control template provided by the PLC provides intuitive menu-drive and/or icon-driven access to process operations via display screens of multiple HMI devices networked to the PLC. In manufacturing environments in particular, HMI devices are typically embodied as touch-screen panels that interface with one or more PLCs. HMI devices are used to monitor the status of and/or control one or more process workstations. For example, an HMI device may be networked to a workstation and used to control individual actuators for that particular workstation, e.g., automated conveyor systems, electric motors, solenoid devices, hydraulic lifts or presses, and/or pneumatic torque wrenches. While HMI devices are widely used in industry, conventional HMI control templates and the integration of such templates within a process environment remain less than optimal, particularly in terms of dynamic adaptability and memory utilization.